Loud-speaker unit



May 31, 1927.

1,630,380 C. R. HANNA LOUD SPEAKER UNIT Filed May 8, 1925 ATTORNEY WITNESSES:

Patented May 31, 1927.

UNITEDl STATES PATENT oFFicr..V

cLINToN n. HANNA, oF wILxINsBURG,

IroUsn ELECTRIC a MANUFACTURING vANIA.

Application mea nay s,

capable of the production of sounds with a minimum amount of distortion.

A'nother object of my invention is to provide a telephone receiver devicey having therein an annular magnet in which one pole is upon the inner annulus and the other pole is upon the outer annulus.

Another object of my invention is to produce a telephone receiver device in which the vibratory diaphragm carries minimum magnetic fluX.

Another object of my invention is to pro.- vide a telephone receiver device in which the steady flux passes through a minimum portion of the diaphragm and in which the vibratory flux passes through a maximuma sound conveying channel is portion of the diaphragm.

Another object of myinvention is to provide a telephone receiver device in which the vibratory flux is by-passed through a magnetic circuit other than that of the permanent magnet.

Another object of my invention is to provide a telephone receiver device in which provided concentric with the electromagnet coil.

A further obi ect of my invention is to. pro- .vide a telephone receiver device having a sound chamber cooperating with a diaphragm in which the sound chamber hasthe shape of -a right cone of low altitude and in which a sound-conveying channel is connected tothe apex of the conical space.

In prior construction of telephone receiver devices, attempts have been made to provide devices lwhich are capable of the translation of substantial amounts of voice frequency electrical energy into sounds of substantial volume. Sounds are most conveniently produced by the electromagnetic reaction between a magnetically permeable diaphragm, a steady magnetic flux and a varymg ux produced by the current to be translated.

Diiiiculty has, however, been experienced PENNsYLvANIA, AssIeNon To WnsTING'- COMPANY, A CoRPoRATIoN or PENNSYL- LoUn-srEAx'ER UNIT.

1925. serial No. 28,792..

in handling suiiicient energy to produce an adequate sound volume without serious diiliculties from distortion and incorrect translation, which produce sounds different in'quality from the original.

.The most serious limitation in the ordinary telephone receiver device has beenthat imposed by through the diaphragm the steady flux which is required to prevent doubling of the sound frequency. In order to obtain adequate movement of a diaphragm it must be thin, else its rigidity will prevent suliicient movement, but after it is made suiiithe necessity of conveying ciently thin it. will carry only a limited amount of magnetic flux Without reaching its saturation point. This ditliculty is further complicated by the fact that the steady flux must be considerably greater than the maximum varying ux. .f,.however, the steady flux could be removed from the diaphragm, leaving only. the varying fluX to pass therethrough, the permeability of the diaphragm is ample for the translation df any reasonable amount of vibratory electric energy.

Other dihculties encountered in the design of telephone receiver devices have been those of providing a sutlicient amount of steady flux in a reasonable weight of material and still other difficulties have been encounteredin the provision of a sound chamber around the ldiaphragm of such shape that maximum utilization of vibratory movements of the diaphragm is made.

My invention provides means whereby the steady flux is substantially removed from the diaphragm; 'only a small annular ring near the center of the diaphragm beingsubject-to the steady lux.

My invention further. provides means .whereby annular magnets of high coercive force material of the ty e disclosed in my .copending application erial No. 734,604, iiled August 28, 1924, `are used. Each of these magnets has one pole at the inner annulus andthe other pole on the outer annulus. Y My invention further provides tubular pole pieces Jfor the permanent magnets upon 'which are wound electromagnet coils for the vibratory electric current.

My invention furtherl provides magnetic shunts for the vibratory flux according to the disclosure of the previously mentioned copending application.

y invention also provides a conical sound space cooperating with the diaphragm, and having a sound conveying 23 channel from the apex thereof. A horn is connected thereto for' obtaining maximum response from a diaphragm according to the copending application of Joseph Slepian and myself, Serial No. 690,405, filed February 4, 1924.

Other objects and structural details of my invention will appear from the following description, whenl read in connection with the accompanying drawing wherein:

Figure 1 is a represent-ation, partially in elevation and partially in axial section of a preferred form of my invention, and a diagrammatic representation of circuits cooperating therewith,

Fig. 2 is a plan view of a receiver device embodying a form of my invention; and

Fig. 3 is an enlarged fragmentary sectional view showing the diaphragm and'4 sound chamber.

In Fig. 1, a telephone receiverrl, is shown associated with a horn 2,'and connected to a radio receiving system 3. The receiver 1 comprises a pair of tubular elements 4 and 5, clamped together by a threaded ring 8 and have, respectively, a smooth shoulder 6 and a threaded shoulderU7. A pair of annular magnets 9 and 10 are inserted within opposite ends of the tubular sections 4 and 5. These annular magnets may be of material of high coercive force'described in my previously-mentioned application, and are magnetized at a suit-able stage in the assemvbly of the device, in such manner that4 the magnetic poles are upon the respective inner and outer annulae, and that one magnet has upon its inner annulus a pole of one polarity and the other magnet has upon its inner annulus a pole of the opposite polarity.

A diaphragm 11, of magnetic material,

shown in greater detail'in Fig. 3, is clamped between theftubular sections 4 and 5, which are also of magnetic material. The tubular pole pieces 14 and 15 are inserted within the inner annulac of the magnets 9 and 10. These pole pieces are somewhat shorter in -length than the members-4 and 5in order that they vmay not interfere with the vibration of the diaphragm by contact with. it.

Upon the pole pieces 14 and 15 are mounted electromagnet coils 16 and 17. The' pole pieces 14 and 15 have formed thereon shoulders 18 and 19 .slightly less in diameter than the inner diameter of the tubular body members 4 and 5. These shoulders 18 and 19 cooperate with the body members 4 and 5 to serve as magnetic shunts. Filler pieces 21 and 22 of slightly conical annular shape are mounted upon the pole pieces 14 and 15 and adapted to lill the inner ends of the tubular pieces 4 and 5. The tubular opening through the pole piece 14 is connected to the inlet of the horn 2 and the tubular opening in pole piece 15 is closed by a plug In the operation of my device, a steady magnetic iiux is established by the magnets 9 and 10 through a magnetic circuit consisting of magnet- 9, tubular piece 4, the edges of diaphragm 11, tubular piece 5, magnet 10, pole piece 15, annular air gap 24, an annular ring portion of diaphragm 11, an air gap 25 and pole piece 14. An additional magnetic path is provided for the magnet 9 through a portion of base 4 across an air gap to the shoulder 18 and pole piece 14.

similar shunt path is provided for the magnet 10. Still another magnetic path is provided for the flux of coil 16 through a portion of the pole piece 14 to the shoulder 18, a small air gap to the tubular piece 4, diaphragm 11, air -gap 25 and back to the pole piece 14. A similar path for the iiux of coil 17 is provided.

The steady flux of magnets 9 and 10 passes direction it may flow through coil 16 inl suchdirection as to strengthen the flux passing from magnet 9 and also tend to cause ux the diaphragm 11 between the end of pole 14 and the tubular portion 4. Simultaneously, the same current flowing in coil ,17 produces a magnetlzation 1n opposltion to the-fiux produced by magnet 10, thereby 'diverting a portion of its iux through the shoulder 19 and increasing the amount of flux which .iows through the diaphragm 11.

.As a result of this action, the diaphragm 11 may be attracted towards the pole piece 14 with an .intensity varying with the strength of the current owing. This attraction causes a movement of the center of the diaphragm towards the pole piece. When a vibratory current is passed through the coils, this movement becomes a vibratory movement corresponding4 to the vibrations of the current. These vibrations move adjacent air, which movement is perceptible as sound.

By' thisl system of construction, iux` cortions in which the permanent iiux and the varying Hux both pass through the diaphragm in the same path.

The 'filler pieces21 and 22 restrict the space in which the diaphragm vibrates to such volume that the maximum vibration of the diaphragm will traverse a major portion of it. In consequence, a maximum displacement ofairinto the tubular centers of the pole pieces is obtained, resulting in a maximum sound amplitude. rIhis sound amplitude is further reenforced by the horn described in my previously mentioned application, whereby maximum loading of the diaphragm is obtained and a maximum etliciency of translation is also obtained. |llhe presence "of the plug 23 prevents the egress of sound energy of opposite phase and thereby prevents that loss of energy. v

By thisV means, I am enabled to provide a telephone receiver device which is capa ble of translating much higher power at much greater efliciency and with much greater accuracy than previous devices.

While I have shown but a single embodi-y ment of my invention in the accompanying drawing it is capable of various changes and modifications therefrom without departing from the spirit thereof and it is desired therefore that only such limitations shall `be imposed thereon as are indicated in the prior art or in the appended claims.

I claim as my invention:

1. telephone receiver device comprisingl anv annular magnet, the outer periphery thereof constituting one pole, the inner periphery thereof constituting the other pole.,

anda magnetizablr case cooperating with said outer pole, and a magnetizable tubular pole piece cooperating with said inner pole and having a magnetic shunt piece extend- *ing toward said case, a magnetizable diaphragm, and a m'agnetizingcoil there-- around. I X 2. A telephone receiver device comprising an annular magnet, the outer periphery thereof constituting one pole, the inner pe riphery thereof constituting the other pole, a magnetizable case cooperatingv with said pole ieee. 6. .i

outer pole, a magnetizable tubular pole lpiece cooperating with said inner pole and said coil.

4. A telephone receiver device comprising I a diaphragm, a supportV therefor, a permanent magnet cooperating therewith, a tabular pole piece between said diaphragm and magnet and an electromagnet coil thereon and a perforated non-conductive disc parallel to and adjacent to said diaphragm, said pole piece being inserted in the perforation therethrough, said tubular pole piece .and said perforated disk being adapted to convey, control, and accentuate sound vibrations produced by said diaphragm.

5. A telephone receiver device comprising a diaphragm,v a tubular pole piece, a magnetizing coil thereon, a conical, non-conductive non-resonantannular disk adjacent said diaphragm, and surrounding the end of said telephone receiver device comprising a diaphragm, a tubular pole piece, a magnetizing c oil thereon, a conical, non-conduc- I tive non-resonant annular disc adjacent said diaphragm, and surrounding the end of said pole piece,`the edge of said disc being closely adjacent to said diaphragm near the edges thereof, and being distant from said Vdiaphragm by less than lg the diameter" thereof at the annulus thereof. 5 I In testimony whereof, I have hereunto subscribed my'name this 29th day of April -CLINTQN R. HANNA. 

